


promises, promises

by robinyourcreator



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Angst, Angst with a Happy Ending, BLOOD FOR THE BLOOD GOD, Byleth and Edelgard are the same age because I do what I want, Byleth is a demon, Childhood Friends, Childhood Trauma, Edelgard fans only, F/F, Hurt/Comfort, Maybe more - Freeform, Or twenty, Revenge, Rhea fucked up, Sothis is a delight and also thirsts for blood, Sothis is a demon, chop chop - Freeform, definitely more actually., dig two graves, dumb byleth rights, just from baby to adult-ish garreg mach era, on a quest for revenge, or demon! as it were, or did she?, we will timeskip eventually but it won't be THE timeskip, we're gonna need a lot of graves here we've got a lot axes to grind
Language: English
Status: In-Progress
Published: 2021-01-19
Updated: 2021-01-19
Packaged: 2021-03-18 07:00:18
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 2,968
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28862955
Author URL: https://archiveofourown.org/users/robinyourcreator/pseuds/robinyourcreator
Summary: Edelgard gave up on the existence of a benevolent goddess long ago. Nothing could be both all powerful and all loving, and yet allow such a cruel and unjust world to exist. After months of unanswered prayers while watching everyone she loved die around her in the dirt and the dark, Edelgard finally finds something to believe in. If prayers and virtue couldn't save her, then blood and promises just might. With the help of the two strange, nonchalantly murderous demon children she just summoned, of course.
Relationships: Edelgard von Hresvelg & Sothis, Edelgard von Hresvelg/My Unit | Byleth, My Unit | Byleth & Sothis
Comments: 10
Kudos: 86





	promises, promises

Byleth dropped to her knees, having finally found a spot out of the wind and out of sight of the Blade Breakers’ campsite, and started digging around in her pack for where she’d stored her flint and tinder. Jeralt had ridden off to deliver word that their latest contract was complete, and would be back in a few hours with their pay and far too many casks of alcohol. Without her father there to break the ice, being in camp with the others was… uncomfortable. It wasn’t that she wasn’t welcome; she was still the captain’s daughter, and a menace with a sword in her own right. None of the mercenaries would ever dare to get on her  _ or _ Jeralt’s bad side.

She was just also the captain’s daughter. The captain's... emotionless, methodical, and murderously efficient  _ twelve year old  _ daughter, which made more than a few of her father’s men uneasy. She’d never quite understood what her age had to do with it. But to avoid awkwardness with her father’s men, when Jeralt wasn’t around Byleth tended to make camp on her own. 

It wasn't just her father's men who had qualms about her and her presence on the battlefield. Even at her tender age, she’d started to develop a reputation as the so-called  _ Ashen Demon  _ of the Blade Breakers. The sight of a blank faced child tearing through enemy ranks with brutal efficiency and covered in blood that wasn’t her own tended to give her opponents pause, and those who made such a mistake on a battlefield rarely lived long enough to regret it. Jeralt had taught her early on to never waste an opening-- anyone trying to hurt  _ her  _ wouldn’t pass up such an opportunity, after all, so neither should she-- and Byleth  _ always  _ took her father’s lessons to heart. 

That was how she'd learned a dozen ways to put a man in an early grave before she’d reached a dozen years of age, after all. 

Byleth quickly started a fire, coaxing a flame from the tinder to the kindling she’d gathered, and took a seat on her pack. Out of sight, but not earshot, of the main camp; she’d be close enough for Jeralt to find her when he came back and far enough away to have some privacy until he did. 

After warming her hands for a moment, she took out her sword and set to work cleaning it. She was finally alone… or as alone as she could be, these days. 

“Not going to celebrate with them, Byleth?” a voice rang out, seemingly out of nowhere until a small, green haired child appeared out of the ether beside her, leaning over Byleth’s shoulder. 

Byleth shrugged. “Hello Sothis,” she said, not taking her eyes off her work as she methodically polished away dried blood from steel. She’d grown used to her incorporeal companion over the past two years, since the first time Byleth had put her father’s lessons to use. 

Sothis had appeared to her when the first drop of blood was spilled, stretching like a cat and watching with idle interest as Byleth slit a man's throat with the very knife he'd threatened her with. He'd said something about a ransom, and 'hold still?' But Byleth hadn't really paid attention once the knife came out. She'd just stabbed her fingers in his eyes and gone from there.

“What a waste of life and blood,” Sothis had drawled, stifling a yawn. “Well, brat? Don’t go wasting the floors with it, too. Clean up the mess you’ve made of the beast.” 

She had been popping up around the times Byleth engaged in her father’s work ever since, only to Byleth’s own eyes and ears. After having cleared out a den of bandits with the Blade Breakers, Byleth had been expecting her to visit. 

A single, small part of her was glad she had.

Sothis huffed and rolled her eyes. “ _ Honestly,  _ child. If those fools can’t appreciate you doing their work for them,” she said, referring to the Blade Breakers camp up the hill, “they can at least be polite.” 

“I don’t mind,” Byleth replied. “It’s not like they’ll be putting out dinner until Dad gets back, anyways.” 

Sothis threw her hands in the air. “ _ Ugh! _ Is food the  _ only  _ thing you care about?” 

“...I also care about Dad? I think.” Byleth paused in her polishing, and took a moment to consider the question. “Your company is nice, too.”

“...Your praise honors me,” Sothis deadpanned, but Byleth had started to notice that the twitching at the corners of Sothis’s mouth generally meant she was pleased, but didn’t particularly want  _ Byleth  _ to know that. 

Sothis settled closer, lying down on the air in front of Byleth and resting her chin on her hands. “You were quite the overachiever today, weren’t you,” she hummed. “I can feel it.”

“Dunno,” Byleth said, having finally cleaned the sword to sparkling. She bent to grab a whetstone from her pack and set to work again with that. “I wasn’t keeping count.” 

“Just how much blood have you spilled with that adorable little sword of yours, hmm? Haven’t you ever wondered?”

“Dunno,” Byleth repeated. “Isn’t always this sword. And I haven’t really kept count on all the other days, either.” 

Letting out a frustrated sigh, Sothis drifted closer. She flicked an incorporeal finger at Byleth’s forehead. “Have you ever wondered why I come to you, Byleth? Or why I come to you when I do?”

“...No?” Byleth blinked slowly, pausing at the end of a long pull of the whetstone. 

“Haven’t you an  _ ounce  _ of curiosity in that thick, emotionless skull of yours, child?” Sothis demanded. 

“Not really?” Byleth shrugged. “I think I do like that you come, though. It’s nice.”

Sothis sputtered. “I am not  _ nice, _ ” she insisted. “I am a  _ parasite,  _ a creature of ashes and death resting where your own pathetic little mortal soul should be.”

“Oh.” Byleth considered that for a moment. “You can keep it. I don’t mind.”

_ “That is not the proper response to being told something else owns your soul, you dolt!” _ Sothis shrieked. 

“...I don’t think I’m very good at proper responses,” Byleth replied, the slightest bit of disappointment seeping into her voice. 

“What I was  _ getting to,  _ you oblivious, obsequious, obnoxious little monster-- is that you’re feeding me, whether you like it or not.” 

Byleth frowned. “Are you hungry?”

“You know what, my dear little monster?” Sothis cocked her head to the side, as if to listen to something only she could hear. “I think I am. And we are going on a  _ hunt,  _ you and I.”

***

It had been one hundred and forty seven days since Edelgard had seen the sun. One hundred and thirty five days since the first of her ten siblings had died. One hundred and twenty six days since the second. And only twelve since the last and youngest two of them. Leaving only Edelgard, alone in the dark.

Aurelia von Hresvelg, only eight and the last of them to be opened up by the strange pale creatures in their cloaks and masks, had never been put back together quite right, coughing and vomiting bile and blackness until she’d grown so weak she had finally drowned in it. 

And Crispin, hardly a year younger than Edelgard at his not-quite-eleven, had been dragged away with their sister’s body, kicking and screaming, and later returned with blood streaming from his eyes and ears, still struggling in the grip of the guards until they tossed him back in his cell so hard that Edelgard heard the snap of bone, leaving her brother in a crumpled heap from which he never rose. 

Edelgard had cried her last tears as they took his body away, and then she cried no more. 

Not when they carved her open for the last time, when saws and scalpels pulled skin and bone and sinew away from her heart or when they pumped boiling blood directly into her veins, burning her alive from the inside out. Not even when, emaciated and wounds still weeping, they left her in her ragged bandages in the dirt for the rats to scurry over in the dark. 

She bled, and she bled, and she bled, and still the sutures never scabbed over. Was it even her blood anymore, with how much they had taken from her and how much poison and fire they had filled her with in return? 

She hugged her arms tight to her chest, her bandages already seeping red and leaving her hands sticky and stained. She had bled, and bled, and bled--  **_and for what?_ **

She was a von Hresvelg, perhaps the  _ last  _ von Hresvelg now. Her blood had to have  _ some  _ worth, what little of it that remained. She remembered, once, she had caught Hubert studying his black magics, and though she had not any aptitude for magecraft whatsoever, he had still explained the topics of his study to her. 

Dark magics, the most dangerous and powerful kinds, kept in vaults and tombs and forbidden books, could be powered not just with magic, but blood and human sacrifice. Doing so, he had warned her, was the greatest taboo any mage could dare commit, and the results were often nearly as destructive to their users as they were to victims. 

But despite its devastating cost, and the risks Hubert had explained to her, that malevolent glee twinkling in his eye at the thought of doing something so forbidden, it had been clear:  _ blood had power.  _

And she, Edelgard realized with a hysteric, nervous laugh bubbling out of her, was practically  _ swimming _ in it, the sutures over her heart weeping her life's blood in long streaks to the floor. She cupped her hands as close to the incisions as she dared, gathering droplets on her fingers and slowly, agonizingly, drawing a circle around her in the dirt. 

“Gods, demons, monsters,  _ whatever you are.  _ If you… If you’re real at all,” she whispered as she went. Long, long ago she had stopped praying or believing in a benevolent Goddess--  _ what benevolence could there be in a god, that allowed what had happened to them?-- _ but blood for blood, an eye for an eye? That she could believe in, that she would gladly give both her eyes and every drop of blood in her body for. “I’ll give anything, everything that I am or will be. I will bleed for you my whole life, no matter how long or short that will be now. Just please,  _ please, _ ” her voice caught, hoarse from disuse and dehydration and desperate, desperate hope, breaking off in a coughing fit.

_ “Please, _ ” Edelgard begged, her stinging eyes screwed shut so no tears would fall. “Make them bleed, too.” 

The next thing she heard was a hiss and a clatter, and she opened her eyes to see two silhouettes beside her in the dark. 

“Um, I’m supposed to say, ah…” the taller one began. That was a child’s voice. She couldn’t be much older than Edelgard, despite the flatness of her tone. Hurried whispering passed between the two strangers in her cell. 

The taller child cleared her throat and began again, still without a trace of emotion in her voice. “Right. I’m supposed to say: ‘that can be arranged, princess.’”

“What can be arranged?” Edelgard demanded, hugging her knees to her chest so they wouldn’t see just how much she was bleeding, too weak to do much else but glare in their direction.

“Gods above and below, this one is almost as stupid as  _ you,  _ Byleth,” said the other one, her voice high and melodious but  _ definitely  _ belonging to someone no older than Edelgard. 

Had her uncle Warped in these children just to mock her for daring to have one last shred of hope? Were they here just to torment her, or was she going to have to watch them die, too?

“I’m not  _ stupid, _ ” Edelgard snapped. “I have no idea how or why you’ve come here.” 

“Because you  _ called  _ us here, you brat, you and your overly simplified but still  _ extraordinarily  _ tempting blood sacrifice-- wait just a moment, little one.” The smaller silhouette leaned in, and suddenly Edelgard noticed that the rude child’s feet weren’t even touching the ground; she was  _ floating.  _

Suddenly the cell was filled with a soft green light, emanating from the strange, fey looking green haired girl staring down at her, her smile too wide, her teeth too sharp-- 

“You can see me now, can’t you,” she crowed delightedly. 

“You can see Sothis?” the taller girl-- _ Byleth _ , Edelgard had heard the other child _ \--who must be Sothis-- _ call her-- said, frowning. She tilted her head to the side quizzically, like a dog unsure of its master’s orders. 

Edelgard squeaked.  _ A demon.  _

Somehow, after moons and moons of worthless prayers, of all her loved ones dying before her in the dark and the dirt--something had answered her. 

She had summoned a demon to her side. 

“...Yes, I can see-- _ and hear _ \-- the both of you,” she said pointedly. 

Byleth straightened, but continued to look at her strangely, still looking faintly bemused. “That’s new. No one’s ever been able to see Sothis before besides me.” 

“Well, my darling little monster,” Sothis crooned, still studying Edelgard like she was about to  _ eat her.  _ “No one has ever summoned me-- _ us-- _ before, either. Certainly not someone with blood so…  _ promising. _ ” 

Edelgard choked back a bitter laugh. Her blood. Of course. The masked men had been endlessly interested in her blood, in taking her apart and taking it from her and stitching and syringing her up of it again. And not just the masked men, apparently.

She’d offered up her blood, and gods damn her, but if whatever manner of man or beast or  _ demons  _ Byleth and Sothis were, if they could make those  _ monsters  _ who had taken her family from her suffer… 

Blood was a price she would gladly pay. 

“You want my blood? You can-- you can  _ have it, _ ” Edelgard stammered, still on the verge of laughing in something like bitterness, hysterics, or both. “Blood for blood, you de-demon.” 

“‘ _ Make them bleed,’ _ ” Sothis quoted, her too-sharp teeth glinting in the green light she’d filled the dungeons with. “Blood for blood it is, little princess.” She turned to her companion. 

“Byleth, be a dear and put my Crest to good use bending those bars out of our way. We have a princess in need of a little rescuing, and a lot of revenge.”

Byleth frowned, but summoned her Crest anyways-- _ the Crest of Flames?!  _ Edelgard noticed with a panic _ \-- _ and did as requested, bending the steel bars like clay. 

Sothis made a dismissive gesture at her, never taking her eyes off Edelgard. “Run along, little one, and get to killing--any creature still scuttling about down here with the worms and the rats is fit only to die with them. The so-called  _ Ashen Demon _ has her work cut out for her. Shoo.” 

Byleth glanced back at them, her frown deepening. “I’m not supposed to kill anyone unless they pull a blade on me or I’m on one of my father’s contracts.” 

“Consider this a contract from  _ me,  _ then, Byleth. Or from our young friend, the Crown Princess of the Adrestian Empire, if you prefer. Look at her, Byleth. They’ve already drawn their own blades on  _ her,  _ made of her the wretched, pitiful thing you see before you. Doesn’t that just make your blood  _ boil  _ with the need for justice?” 

“I don’t know,” Byleth said quietly, her voice so low Edelgard barely heard it. But with one last look at them, she left anyway, her sword clutched tight in hand as she ran down the hall of cages. 

For a moment, they were at a stalemate--Sothis watching Edelgard, and Edelgard watching Byleth, spellbound, at the child hardly an inch taller than her running off to execute Edelgard’s enemies for her.

“I am  _ not  _ a ‘wretched, pitiful thing--’” Edelgard snapped as soon Byleth was out of sight. 

“Hmm, perhaps I misspoke. Well! No harm done, I’m sure. You’re strong enough to still be alive in this miserable hole. I’m sure you’re strong enough to not let a few words hurt you.” 

“I may be weak before the likes of  _ you,  _ demon,” Edelgard spat. “But I’m no--” 

She cut off, suddenly, at the sounds of screams echoing down the hall. 

From where Byleth had just gone.

Sothis’s grin widened, and she leaned closer, until she was almost nose to nose with Edelgard, seemingly unperturbed by, or even  _ enjoying  _ the screaming. “You should know, little one, of a certain saying, I’m sure. ‘An eye for an eye makes the whole world blind.’” 

“And what of it?” Edelgard demanded. 

“An eye for an eye, a pound of flesh for a pound of flesh,  _ blood for blood.  _ Such ideals will bleed the whole world, if they’re embraced.” 

“Then maybe it  _ deserves to bleed, _ ” Edelgard snapped, too loud over the sudden lack of screaming down the hall. 

Sothis laughed, she laughed and laughed and laughed, leaning back and hugging her belly and rolling in the air with it. She wiped tears from her eyes, finally recovering from her laughing fit. 

“I  _ like  _ you, little princess. Oh, I think we’re going to get along very nicely. ” Sothis leaned in again, reaching out one ghostly, ethereal hand, and passing it through Edelgard’s knees as she froze in place, ran a single finger along the stitches that ran from Edelgard’s navel to sternum, gathering up her blood like raindrops on a windowpane.

“If we’re to make the whole world bleed, little one, oh what a joy, what a pleasure, what a  _ delight, _ ” Sothis crooned as she licked the blood off her fingers, “that we will be starting with those most richly deserving of it.”

  
  
  



End file.
